Automatic pathway and waypoint generation and navigation method

ABSTRACT

A navigation system for use in a luminal network of a patient, such as the airways, that is able to analyze a three-dimensional model of the luminal network and automatically determine a pathway from an entry point to a designated target. The system further automatically assigns waypoints along the determined pathway in order to assist a physician in navigating a probe to the designated target.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Pat. No. 8,218,846 filed May 14, 2009 and provisional Patent Application Ser. No. 61/053,523, filed May 15, 2008, both entitled Automatic Pathway And Waypoint Generation And Navigation Method, and which are hereby incorporated by reference.

BACKGROUND

Breakthrough technology has emerged which allows the navigation of a catheter tip through a tortuous channel, such as those found in the pulmonary system, to a predetermined target. This technology compares the real-time movement of a locatable guide (LG) against a three-dimensional digital map of the targeted area of the body (for purposes of explanation, the pulmonary airways of the lungs will be used hereinafter, though one skilled in the art will realize the present invention could be used in any body cavity or system: circulatory, digestive, pulmonary, to name a few).

Such technology is described in U.S. Pat. Nos. 6,188,355; 6,226,543; 6,558,333; 6,574,498; 6,593,884; 6,615,155; 6,702,780; 6,711,429; 6,833,814; 6,974,788; and 6,996,430, all to Gilboa or Gilboa et al.; U.S. Published Applications Pub. Nos. 2002/0193686; 2003/0074011; 2003/0216639; 2004/0249267 to either Gilboa or Gilboa et al; as well as U.S. patent application Ser. No. 11/939,537 to Averbuch et al. All of these references are incorporated herein in their entireties.

Using this technology begins with recording a plurality of images of the applicable portion of the patient, for example, the lungs. These images are often recorded using CT technology. CT images are two-dimensional slices of a portion of the patient. After taking several, parallel images, the images may be “assembled” by a computer to form a virtual three-dimensional model of the lungs.

The physician then takes this virtual model and, using the software supplied with the navigation system, plans a path to the target. Planning the path to the target involves creating a patient file and selecting and saving various waypoints along the path to the target. The physician also selects and saves various registration points used by the software to register the virtual model to the actual patient in the upcoming procedure.

Typically, there is only one path that leads to the target, unless the target is very large. In the airways and vasculature of the body, the body lumina do not split and then rejoin downstream. The branches of a tree provide a good analogy: for any given leaf on a tree, there is only one combination of branches that lead to that leaf Hence, the step of pathway planning is a time-consuming step that would be avoided if automated.

Additionally, the present systems provide guidance to the target, but not necessarily to the waypoints along the way. Instead of focusing on the target, it would be advantageous to provide navigation guidance to each of the intermittent waypoints, thereby treating each successive waypoint as a target, then, after the waypoint is reached, changing the target to the next waypoint.

SUMMARY

In view of the foregoing, one aspect of the present invention provides a system and method for automatically planning a pathway from an entry point in a patient to a target through a luminal network.

Another aspect of the present invention automatically generates the various waypoints between a starting point and the target.

Another aspect of the present invention provides a system and method for providing navigational cues to a target via the plurality of waypoints. The cues are provided in such a manner that the next waypoint in a path is automatically detected and treated as a destination. Navigational cues are provided to that waypoint until it is reached. The system then selects the next waypoint along the path and provides navigational cues to that waypoint. This continues until the actual target is reached.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flowchart describing a general step of a method of the present invention;

FIG. 2 is a flowchart describing a general step of a method of the present invention;

FIG. 3 is a flowchart describing a general step of a method of the present invention;

FIG. 4 is a user interface of an embodiment of the system of the present invention; and

FIG. 5 is a user interface of an embodiment of the system of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Generally, the present invention includes a system and method for constructing, selecting and presenting pathway(s) to a target location within an anatomical luminal network in a patient. The present invention is particularly, but not exclusively, suited for guiding and navigating a probe through the bronchial airways of the lungs. The present invention includes a preoperative and an operative component. The preoperative component is conducted prior to navigation and can be categorized as “Pathway Planning” The operative component is conducted during navigation and can be categorized as “Navigation.”

Pathway Planning

The pathway planning phase includes three general steps, each of which is described in more detail below. The first step involves using a software graphical interface for generating and viewing a three-dimensional model of the bronchial airway tree (“BT”). The second step involves using the software graphical interface for selection of a pathway on the BT, either automatically, semi-automatically, or manually, if desired. The third step involves an automatic segmentation of the pathway(s) into a set of waypoints along the path that can be visualized on a display. It is to be understood that the airways are being used herein as an example of a branched luminal anatomical network. Hence, the term “BT” is being used in a general sense to represent any such luminal network, and not to be construed to only refer to a bronchial tree, despite that the initials “BT” may not apply to other networks.

First Step—BT Generation

Referring now to FIG. 1, there is shown a flowchart describing the first step-using a software graphical interface for generating and viewing a BT. At 20, the first step begins with importing CT scan images, preferably in a DICOM format, into the software. The data may be imported into the software using any data transfer media, including but not limited to CDs, memory cards, network connections, etc.

At 22 the software processes the CT scans and assembles them into a three-dimensional CT volume by arranging the scans in the order they were taken and spacing them apart according to the setting on the CT when they were taken. The software may perform a data fill function to create a seamless three-dimensional model.

At 24, the software uses the newly-constructed CT volume to generate a three-dimensional map, or BT, of the airways. The three dimensional map can either be skeletonized, such that each airway is represented as a line, or it may be include airways having dimensions representative of their respective diameters. Preferably, when the BT is being generated, the airways are marked with an airflow direction (inhalation, exhalation, or separate arrows for each) for later use during the pathway generation step. It is envisioned that this step is optional. The CT volume may be used as it is.

At 26, the software displays a representation of the three-dimensional map on a user interface, such as a computer monitor.

Second Step—Pathway Selection

Referring now to FIG. 2, there is shown a flowchart describing the second step-using the software graphical interface for selection of a pathway on the BT. At 40, the second step begins with a determination, by the software, of an appropriate pathway to a selected target.

In one embodiment, the software includes an algorithm that does this by beginning at the selected target and following lumina back to the entry point. Using the airways as an example, the target is first selected. The software then selects a point in the airways nearest the target. If the point closest to the target is in an airway segment that is between branches, the software has to choose between two directional choices. If the airways of the BT were marked with airflow direction, the software moves in the opposite direction of the arrows, thereby automatically generating a pathway to the entry point.

Alternatively, the pathway to the target may be determined using airway diameter. Moving toward the entry point (the trachea) results in an increased airway diameter while moving distally results in a decreased airway diameter. Hence, the software could choose to move in the direction of increased airway diameter. If the point closes to the target is in an airway segment that includes one or more branches, the choices are more numerous but the following the path of the greatest increase in airway diameter will still result in the correct path to the entry point.

Though unlikely, in the event that an incorrect path is taken, the software would eventually detect an inevitable decrease in diameter, if this is the case, the software would automatically abort that path and revert to the last decision-making point. The algorithm will resume, blocking off the incorrect path as an option.

At 42, after the pathway has been determined, or concurrently with the pathway determination, the suggested pathway is displayed for user review. Preferably, the entire BT will be displayed with the suggested pathway highlighted in some fashion. The user will have zoom and pan functions for customizing the display.

At 44, the user is given the opportunity to edit and confirm the pathway. There may be reasons an alternative pathway is desirable. For example, though the targeted lesion is closest to a particular airway, there may be an artery or a lobe division between the selected airway and the target. Hence, it is important to provide the user with editing ability.

Third Step—Waypoint Selection

Referring now to FIG. 3, there is shown a flowchart describing the third step—using the software to automatically generate waypoints. At 60, the third step begins by designating each of the decision making points from 40 of step 2 as waypoints. This may happen concurrently with 40. Each time the software, while navigating backwards toward the trachea, was presented with navigational choices, the user navigating toward the target will necessarily also be presented with choices. Hence, it is logical to designate those decision-making points as waypoints along the path to the target.

At 62, the waypoints appear on the suggested pathway, and may be labeled in such a way as to distinguish them from each other. For example, the waypoints may be numbered, beginning at 1, in the order that they appear. Preferably, the waypoints are positioned just downstream of each bifurcation, instead of at the bifurcation. In this way, providing navigation directions to the waypoint results in the probe being positioned in the appropriate airway once the waypoint has been reached. Hence, the physician can begin navigation to the next waypoint by simply advancing the probe without being concerned about advancing down an incorrect airway.

At 64, the user is given the opportunity to edit the waypoints. It is understood that the second and third steps may occur concurrently. If the user is editing the pathway to the target, the user will also be selecting alternative waypoints, as one in the art will realize.

Fly-Through Feature In addition to the editing features described above, the software presents a “fly-through” feature that presents the user with the opportunity to view the user interface as it would appear from start to finish if the procedure was performed as planned. A preferred embodiment of one view the user interface is shown in FIG. 4.

The interface 80 is divided into four quadrants, 82, 84, 86 and 88. The upper-left quadrant 82 is a lateral view of the CT volume of the lungs, i.e. as though looking parallel to the spine of the patient. The lower-left quadrant 84 is a birds-eye view of the CT volume of the lungs. The upper-right quadrant 86 is a side view of the CT volume of the lungs. The lower-right quadrant 88 is a three-dimensional perspective view inside a virtual airway of the BT. Cross-hairs 90 span over all of the quadrants to show the present location of the LG. The cross-hairs 90 in quadrant 88 are shown in a perspective format.

Navigation

The heading “Navigation” refers to the processes occurring during the actual procedure. Referring now to FIG. 5, there is shown a user interface 100 that assists the user in navigating to the target. This view of the user interface 100 includes four quadrants 102, 104, 106, and 108. The images shown in each quadrant are preferably customizable. Hence, any of the aforementioned views from interface 80 may be displayed. However, pertinent to the navigation discussion is the view shown in the lower-right quadrant 108.

Quadrant 108 is shown as displaying an LG steering indicator. The destination 110 appears as a circle which floats over the quadrant 108 and moves when the LG is turned. The destination 110 represents the next waypoint to which the user is navigating, or the final destination (targeted lesion) in the event that the last waypoint has been passed.

When the distal tip of the LG is pointing directly at the destination 110, the destination 110 appears in the center of the circle 112. If the LG is not pointing directly at the destination 110, the destination 110 is located in a representative location in or out of the circle 112. For example, if the LG is pointing down and right of the destination 110 in the body (in other words, the destination 110 is above and left of where the LG is pointing), the destination 110 on the display in quadrant 108 will appear above and left of the center of the circle 112. If the LG is deflected away from the destination 110 far enough, the destination 110 may not even appear in the quadrant 108. For this reason, a guide arrow 114 appears somewhere on the circle 112. The guide arrow 114 tells the user which direction the LG must be deflected to align the tip with the destination 110.

Although the invention has been described in terms of particular embodiments and applications, one of ordinary skill in the art, in light of this teaching, can generate additional embodiments and modifications without departing from the spirit of or exceeding the scope of the claimed invention. Accordingly, it is to be understood that the drawings and descriptions herein are proffered by way of example to facilitate comprehension of the invention and should not be construed to limit the scope thereof. 

We claim:
 1. A method of accessing a target in a luminal network comprising: constructing a three-dimensional model of the luminal network; identifying a target in the luminal network to be accessed; calculating a path through the luminal network from the target to an entry point, the path being identified through determination of change in lumen size; displaying one or more visual representations of the path through the luminal network; inserting a locatable guide into the luminal network; and advancing the locatable guide through the luminal network following the calculated path on the display.
 2. The method of claim 1, further comprising calculating one or more way points within the luminal network between the target and the entry point.
 3. The method of claim 2, wherein the way points are located immediately following a bifurcation in the luminal network.
 4. The method of claim 2, further comprising displaying the way points on the one or more visual representations of the path through the luminal network.
 5. The method of claim 4, further comprising locating a way point in the visual representation such that its locations indicates the direction of travel necessary for the locatable guide to reach the way point.
 6. The method of claim 4, wherein when the locatable guide is inserted into a bifurcation leading away from the way point, the way point disappears from the visual representation of the path.
 7. The method of claim 2, wherein the way points are automatically generated.
 8. The method of claim 1, wherein the three-dimensional model is formed from CT images.
 9. The method of claim 1, comprising displaying at least one visual representation of the three-dimensional model.
 10. The method of claim 9, wherein the visual representation is a three-dimensional perspective view of the interior of the luminal network.
 11. The method of claim 1, wherein the luminal network is the bronchial airway of the lungs.
 12. The method of claim 11, wherein a user can edit the calculated path.
 13. The method of claim 1, wherein in calculating the path the path is defined by increasing luminal diameter from the target to the entry point.
 14. The method of claim 13, wherein the calculating the path further comprises: determining a luminal diameter of the luminal network proximate the target; selecting a point within the luminal network proximate the target and determining its diameter; determining whether the lumen diameter has increased or decreased as compared to the luminal diameter at the target; iterating the diameter determination and point selection steps such that each successive luminal diameter is larger than the preceding luminal diameter until the entry point is achieved.
 15. The method of claim 14, where in if a luminal diameter of a point is determined to be smaller than the preceding point, the point is eliminated from the path and the selecting and determination steps are restarted from the preceding point. 